1. Field of the Invention
The present invention is generally concerned with clutch release bearings, in particular those for automobile vehicles.
It is more particularly directed to so-called "pull" type clutch release bearings which are designed to operate in traction on the clutch release device of the clutch to be operated and which are coupled to this device for this purpose.
2. Description of the Prior Art
In some clutch release bearing assemblies, and in particular in the clutch release bearing assembly described in French Pat. No. 2,304,826 and that described in commonly assigned with this invention copending U.S. patent application Ser. No. 683 390 of Dec. 19, 1984, it has been proposed to use between the clutch release bearing and the clutch release device to be operated, in order to couple the clutch release bearing to the clutch release device, a part preferred to hereinafter for convenience only as the "coupling part" or "action part" which, appropriately attached to the clutch release device, comprises on the side of the latter opposite the clutch release bearing a radial bearing flange through which it is adapted to operate on it, in cooperation with fastening means operative in traction between a coupling part of this kind and a part referred to hereinafter for convenience only as the "drive part" forming part of the clutch release bearing, adapted to provide an axial coupling between said parts in the axial direction from the clutch release device to the clutch release bearing.
In the above-mentioned French patent and U.S. patent application the fastening means operative in traction employed generally comprise an annular coupling member which is elastically deformable in the radial direction, such as a simple ring, for example, and which is at least partially inserted radially into an annular retaining groove formed for it on either of the parts to be fastened together in traction, and a substantially transverse drive bearing surface on the other of these parts with which said coupling member cooperates in axial bearing engagement in the axial direction corresponding to the required axial coupling.
A particular advantage of an arrangement such as this is that it enables the clutch release device of the clutch to be operated to be fitted with the coupling part in advance, even before the corresponding clutch cover assembly is put together, and then, at the final assembly stage, the clutch release bearing to be engaged with the coupling part and thus with the clutch release device, by means of a simple clipping action.
Although the required coupling between the clutch release bearing and the clutch release device of the clutch to be operated is thus very easily procured, this does not apply for the converse process, meaning the process necessary to decouple the clutch release bearing and the clutch release device.
Failing other measures, it is normally necessary to demount the clutch beforehand in order to gain access from the front, that is to say from the clutch release device side, to the coupling member in order to be able to cause it to retract elastically to achieve the necessary decoupling.
To overcome this difficulty it is proposed in the aforementioned U.S. patent application to use a mobile part to delimit the retaining groove; this so-called decoupling part, which is in the form of a bush, is normally spaced axially from the coupling member and it is sufficient to displace it axially towards the coupling member to expel it from the retaining groove and so bring about the necessary decoupling.
Although it has proven satisfactory, an arrangement of this kind does raise problems.
In particular, a tool is needed for maneuvering the decoupling part, which makes this maneuver relatively difficult.
In the European patent application filed Nov. 10, 1983 under the number 83306880.2 and published under the number 0 110 602 there is described an arrangement with which, both for decoupling and coupling, it suffices to procure appropriate axial movement of the clutch release bearing relative to the clutch release device of the clutch to be operated, the axial movement to be applied to the clutch release bearing in this way being very simple to apply blind using a control member, in practice a clutch release yoke, usually associated with it.
Using this arrangement there is associated with the coupling member an annular decoupling member which is fitted in advance to that of the parts to be fastened together in traction which comprises the drive bearing surface, at a distance from this surface, and with which said coupling member may become engaged as a result of sufficient axial movement of the clutch release bearing in the axial direction away from the bearing surface, provided that the coupling member is stressed.
The coupling member having been stressed by the decoupling member in this way, it entrains the decoupling member with it when the clutch release bearing is agains subjected to an axial displacement in the axial direction towards the drive bearing surface but, because of the fact that it is stressed, it then escapes from this drive bearing surface which brings about the necessary decoupling.
However, being entrained by the coupling member, in this same movement the decoupling member itself escapes from the part to which it was initially fitted and recoupling becomes impossible unless the decoupling member is first detached from the coupling member and both these members returned to their initial position, or new members substituted for them, which entails operations that are particularly difficult to carry out.
On vehicle assembly lines it may be advantageous to be able to carry out recoupling after decoupling, however.
After coupling the clutch release bearing to the clutch release device of the clutch to be equipped, other assembly operations are carried out on such assembly lines, for example the fitting of the clutch cable controling the assembly, and during such operations accidental action on the clutch release yoke may inadvertently decouple the clutch release bearing.
In commonly assigned with this invention French patent application No. 85 09883 filed June 28, 1985, published as French Publication No. 85 09883 on Apr. 3, 1987, there is proposed an arrangement permitting reversible coupling and/or decoupling to be carried out in a particularly simple and advantageous manner.
Using this arrangement there is associated with the coupling member, as previously, an annular decoupling member but this decoupling member is mounted to be movable axially in a groove from which it cannot escape.
The groove is formed in that of the parts to be fastened together in traction which comprises the drive bearing surface and the drive bearing surface forms part of one its flanks.
The decoupling member conjointly features a frustoconical bearing surface which diverges radially from the bottom of the groove in which it is disposed in the direction towards the drive bearing surface and the circumference of which axially nearest the drive bearing surface is at least level with the circumference forming the free edge of the latter.
When decoupling is required, it is sufficient, as previously, to operate on the clutch release bearing in such a way that the coupling member becomes engaged with the decoupling member.
However, this engagement of the coupling member with the decoupling member is obtained through the frustoconical bearing surface of the latter so that when the clutch release bearing is again moved axially in the axial direction towards the drive bearing surface, in order to bring about the necessary decoupling, the decoupling member which butts up against the drive bearing surface causes, through its frustoconical bearing surface and while remaining in place within the part to which it is fitted, sufficient retraction of the coupling member for the latter to escape from the decoupling member and the drive bearing surface and thus from the part comprising this drive bearing surface.
The decoupling member having remained in place, recoupling is possible.
The arrangement described in French patent application No. 85 09883 is suited only to the case where the coupling member is of one of the types described in the aforementioned French Pat. No. 2 304 826, that is to say to the case where this coupling member comprises a substantially frustoconical washer which has one of its edges engaged in the associated retaining groove and features along its other edge, substantially aligned with it, lugs through which it is adapted to cooperate in axial bearing engagement with the drive bearing surface and lugs which, disposed at an angle to the aformentioned lugs, are also engaged in the retaining groove, on the side opposite the substantially frustoconical washer from which they originate.
It does not suit the case where the coupling member is a simple ring, that is to say the case where the coupling member is in the form of a torus, for example in the form of a torus of circular transverse cross-section.
An object of the present invention is an arrangement suited to a case of this kind.